Understanding Your Menstrual Cycle in Perimenopause

Are you noticing changes to your menstrual cycle since moving into your 40s? Heavy periods, painful periods, clotting, longer or shorter bleeds, longer or shorter cycle lengths. These are all common things to start experiencing in perimenopause. Understanding your menstrual cycle in perimenopause is so important for all cycling women. Why? Because as you move past mid to late 30s and into your 40s, your menstrual cycle changes.

In this blog, I explain what’s different about your menstrual cycle in perimenopause and how you can support it.

What exactly is the menstrual cycle?

A healthy menstrual cycle is an ovulatory cycle, where ovulation is the main event, leading to the release of progesterone. It’s possible to have non-ovulatory cycles, where ovulation does not occur, however this isn’t the ideal scenario for health.

From your first every period as a teen right up to your last ever period, your menstrual cycle is orchestrated by continuous communication between your brain and your ovaries. All month long, the brain sends chemical messengers to the ovaries with instructions to release oestrogen (oestradiol) and trigger ovulation (the release of eggs from the ovary).

The process of ovulation triggers the release of progesterone.

If there is no fertilisation of an egg and pregnancy does not occur, progesterone levels drop triggering the start of your next period (day 1 of a new cycle) as the lining of the uterus sheds.

How Your Menstrual Cycle Changes in Perimenopause

As you move into perimenopause, the communication between your brain and ovaries starts to change. More specifically, the brain doesn’t communicate as clearly or the ovaries do not hear as well as they did before. This is similar to how things were when you first started having periods as a teen (puberty). This is why during your first year or more of puberty, periods were irregular, heavy, painful, and PMS quite significant. Remember?

Perimenopause is like your second puberty!

For the first couple of years as a teen, your brain-ovary communication was adjusting to having moved into reproductive years. Oestrogen was fluctuating erratically and progesterone wasn’t always made (you weren’t always ovulating). Remember the irregular cycles, heavy painful periods, clotting, breast tenderness, headaches and mood swings as a teen?

From around age 35, brain-ovary communication starts breaking down in a similar way to what was happening at puberty. Causing many of the same symptoms all over again! This is how we can liken perimenopause to ‘second puberty’ or ‘puberty in reverse’.

As women move from their 30s into their 40s, they start to experience breast pain they either never had before or not since their teens. Plus mood swings and even rage, headaches or migraines, anxiety, irritability, and new sleep issues. Growth of fibroids and cysts can also be common.

How a Healthy Menstrual Cycle looks

For the most part, before perimenopause you had a more gentle ebb and flow of oestrogen throughout the cycle. Ovulation occurred about half way through the cycle, followed by a lovely surge of progesterone during the second half.

The menstrual cycling during regular cycling years

NOTE: This diagram is showing an average 28 day cycle but normal cycles range from 25 – 35 days.

In the diagram you can see that oestrogen dominates in the first half (follicular phase). It ramps up just before ovulation to stimulate the release of an egg. Then, progesterone dominates in the second half of the cycle (luteal phase).

Progesterone is ONLY made after (as a result of) ovulation. Then, towards the end of the luteal phase levels of oestrogen and progesterone fall (to their lowest levels in the cycle). This triggers the start of your next period (day 1 of a new cycle). Then, oestrogen gradually starts to climb again and you won’t see progesterone again until you ovulate in about two weeks time.

Follicular Phase

During the first 14 (ish) days of the cycle, follicle stimulating hormone (FSH) is released (instructed by the brain), stimulating ovarian follicles to produce oestrogen. During this phase, oestrogen is building up the tissue on the wall of your uterus (womb), almost like building the bricks for a healthy, fluffy endometrium in preparation for implantation and housing of a fertilised egg. Oestrogen surges just before ovulation (in order to assist the ovulation process).

Luteal Phase

Then, in the last two weeks (ish) of the cycle progesterone is released (if you ovulated). Progesterone stabalises the wall (uterine lining) and ensures oestrogen does not thicken it too much. The release of progesterone basically shuts down oestrogen production and ensures the next menstrual bleed doesn’t start too early or that any irregular/early spotting occurs.

So, progesterone protects your uterus from developing too much or thick of an inner lining from the exposure to oestrogen. It makes sure the cells of the uterine lining shift from “grow, grow, grow” to “mature and prepare for the next stage”, which is either a menstrual bleed or pregnancy. Without progesterone, a heavy period with clotting is likely more likely, as well as breast pain and PMS. This is why the process of ovulation is about so much more than just fertility. Monthly ovulation is health.

How you make progesterone

After ovulation, a mature ovarian follicle ruptures. This ruptured follicle transforms into a temporary endocrine gland known as the corpus luteum. Ovulation is essential to the production of this gland, and this gland is essential for progesterone production.

Yes, the role of progesterone is to support pregnancy should your egg become fertilised. However, fertility aside, we WANT to make progesterone every single month because it also balances oestrogen. Balanced/opposed oestrogen prevents the situation of unopposed oestrogen or “oestrogen dominance” in the second half of the cycle. Unopposed oestrogen causes mood swings, breast pain, heavy and painful periods, headaches, and sleep issues.

Additionally, progesterone is important for your overall sense of equilibrium and well-being. It provides a sense of contentment, supporting sleep, boosting metabolism and thyroid function, preventing fluid retention and supporting cognition. It increases the calming, anti-anxiety brain chemical GABA, which calms the nervous system and promotes good sleep.

A Monthly Bleed Doesn’t Always Mean You Ovulated

Your cycles can appear normal even though you haven’t ovulated, known as non- or an-ovulatory cycles. One way to know if you are ovulating each month or not is to track your basal temperature each morning (as soon as you wake, before getting out of bed). Because when progesterone is made your body temperature rises slightly. Therefore, if you are seeing a slight increase in your baseline temperature just after your estimated ovulation day that remains sustained throughout your luteal phase, it’s likely that you ovulated (and thus made progesterone). A big indicator of having NOT ovulated is new or worse PMS with breast pain, followed by a heavy and or painful period.

The menstrual cycle in perimenopause

Perimenopause is much rockier and more difficult than menopause, because hormones fluctuate, month-to-month, sometimes mildly and sometimes wildly.

The menstrual cycle through the lifespan (including perimenopause)

In this diagram, you can see the gentle ebb and flow of oestrogen in the reproductive years (the red dotted line) compared to an erratic roller coaster in perimenopause. What you can also see is healthy, consistent progesterone (blue line) in your 20s and 30s compared to a decline of this wonderful hormone in perimenopause.

The change in brain to ovary communication in perimenopause creates three main issues with oestrogen that cause many of the symptoms and changes experienced here, they are;

  1. Erratic fluctuations (the oestrogen roller coaster)
  2. Oestrogen dominance in the second half of the cycle
  3. Oestrogen excess

On the roller coaster, oestrogen levels can soar three times higher than ever before and crash to almost nothing.

These erratic highs and lows bring changes to your cycles and periods, such as;

  • New or worse PMS including mood swings (including rage!)
  • Breast pain
  • Heavy and or painful periods
  • Clotting, cysts
  • Headaches or migraines
  • Sleep issues
  • Anxiety
  • Brain fog
  • Low energy and fatigue
  • Hot flushes and night sweats
  • Histamine or mast cell reactions

Add to this, symptoms of having not made progesterone, some or many months, such as:

  • Insomnia
  • Anxiety
  • Irritability
  • Migraines
  • Water retention / puffiness
  • Irregular periods, shorter cycles and spotting between periods

Perimenopause is the rocky road to menopause

During regular reproductive years (approx 18-35), progesterone calmed the nerve cells in your brain and nervous system. It also stimulated a molecule called BDNF, which is important for cognition, e.g., clarity, memory and learning.

Oestrogen supported the energy system of the brain by allowing glucose to efficiently get into brain cells for energy. It stimulated the mitochondria in your brain cells (tiny energy powerhouses). It reduced inflammation, regulated your circadian rhythm (for good sleep), and boosted the happy chemical serotonin.

Research suggests that the brain undergoes a massive rewiring process during perimenopause and the first few years of menopause. Which causes many of the symptoms and makes them more pronounced during the recalibration phase.

What can you do?

Whilst perimenopause IS a natural transitional phase, it’s also phase of biological rough waters. BUT…it CAN be navigated optimally with a smart captain at the helm of the ship (You!)

Symptoms are temporary (thank goodness!) and respond to simple diet and lifestyle habit interventions that can support the 3 main issues with oestrogen and the production of progesterone (ovulation) as many months as possible.

It is up to you to decide whether or not you want to take action and make the changes necessary for a MUCH smoother and enjoyable ride in your 40s AND transition into menopause and post-menopause when the time comes.

In perimenopause, you want to leverage diet and lifestyle habits that can help to:

  • prevent the oestrogen rollercoaster from spiking too high and too low, which will keep symptoms of high and low oestrogen in much better check
  • Prevent oestrogen dominance by helping your body to make progesterone as many months as possible (by supporting ovulation)
  • Support ovulation so that you make progesterone for its wonderful symptom-reducing and health-protective benefits
  • Prevent or reverse (manage) insulin resistance, which makes all symptoms worse, puts your current and future health at risk and results in excess belly fat

Read my previous blog called ‘How to Get Rid of Perimenopausal Symptoms’ here for tips on what you can do for a much better menstrual cycle in perimenopause.

Hi, I'm Francesca

I’m a Registered Nutritional Therapist who helps womens in their 40s find vibrant health and vitality, and thrive through perimenopause and beyond.

With nearly 10 years of experience working with hundreds of people, I empower and support women to support their bodies and hormones for a smooth and happy ride in their 4os.

Through our work together, clients have improved their energy, their periods and cycles, their mood, sleep, brain fog and digestion, and learned how to better manage their weight.

I am here to help you get back to YOU so you can have a fantastic time in your 40s.

My signature nutrition and lifestyle coaching approach to supporting women with their health and wellbeing is refreshing, down-to-earth and realistic.

Download the Free Guide

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